Active matrix display devices, such as liquid crystal display devices and organic electroluminescence (EL) display devices, include a thin-film transistor (TFT) substrate in which TFTs are formed as switching elements or drive elements.
For example, Patent Literature (PTL) 1 describes an active matrix organic EL display device including a TFT substrate.
A plurality of conductive layers including TFT electrodes, lines, etc. are formed in the TFT substrate. An insulation layer composed of a silicon oxide film, a silicon nitride film, or the like is formed between the conductive layers, as an interlayer insulation film.